However, the Rogue Valley's largest fire most likely was "man-made," according to ODF District Forester Dan Thorpe.

A 60-acre wildfire ignited just after 4 p.m. on the north side of Lost Creek Lake outside Shady Cove. The blaze sent a thick column of gray smoke high above the lake as it chewed its way up a steep ridge.

ODF enlisted helicopters, bulldozers and a bomber plane that strafed the flames with retardant throughout the afternoon, Thorpe said.

"We acted aggressively on this one and will most likely work on it throughout the night," Thorpe said.

ODF is investigating the cause of the blaze, Thorpe said.

The heat wore on the ODF and Jackson County Fire District 6 crews throughout the afternoon, Thorpe said.

"It's hard to do anything productive for any length of time when it's that hot," Thorpe said. "It was brutal work."

Thorpe advised drivers to avoid Takelma Drive today as it serves as the staging area for the fire crews.

ODF was well-prepared to tackle the blaze, Alexander said.

"We are always ready this time of year, but when it's been this hot we take extra levels of precaution," Alexander said.

The local ODF office sent seven firefighters to a 3,400-acre wildfire to northeastern Oregon earlier this week.

Three of those firefighters will be returning sometime today in case they're needed locally, Alexander said.

In other fires across the region, a blaze burning near the popular fly-fishing section of the North Umpqua River in southwestern Oregon has grown to 1,630 acres, and the U.S. Forest Service says smoke in the air has grounded helicopters and air tankers called in to fight it.

Umpqua National Forest spokeswoman Debra Gray said Wednesday there are no evacuations in the sparsely populated area about 30 miles east of Roseburg, but state Highway 138 remains closed between Susan Creek Campground and Steamboat Inn. The Williams Creek and Bogus Creek campgrounds are closed, as well as some forest roads and trails.

A regional fire management team has been called in to handle the Williams Creek fire, which broke out Tuesday. The cause is under investigation, but there were no reports of lightning.

Today could be the last of the triple-digit days, Nelaimischkies said. The temperatures could settle into the mid-90s through the weekend.

ODF helicopters will buzz the skies this morning looking for fires if there are reports of lightning Wednesday night, Alexander said.

"With this heat there is a good chance these storms will cause fires," Nelaimischkies said. "It's been a pretty quiet fire season up until now."